In certain cellular communications networks, the network operator allocates a pool of cell identifiers, and each base station uses one of these identifiers in its transmissions. The number of available identifiers is less than the number of base stations, and so the identifier used by a base station will probably also be used by other base stations. Steps can therefore be taken to ensure that the identifier used by a base station will not also be used by other nearby base stations.
Each base station also compiles a list of its neighboring cells, to be used when a mobile device is preparing a handover from one cell to another. The presence of multiple nearby base stations using the same cell identifier means that it is not always possible for the base station to compile a neighbor cell list that accurately reflects the state of the network. A neighbor cell list may be complied based on measurement reports received from a wireless device, with the measurement reports containing information about particular base stations. The presence of two base stations using the same cell identifier may then mean that the received information is associated with the wrong base station.